[0001] The present disclosure relates to a method for filling and/or refilling a multiple-reservoir
infusion pump with therapeutic agents.
[0002] Implantable infusion devices are used to provide patients with a long term infusion
of a therapeutic agent. Implantable infusion devices are e.g. used in intrathecal
drug delivery systems (IDDS) to treat chronic pain. These systems deliver anesthetic
agents from a reservoir through a catheter to the dorsal horn of the spinal cord.
[0003] The implantable infusion device contains a reservoir which is sealed by and accessible
through a septum. The reservoir is typically refilled by injecting a hypodermic needle
through a patient's skin and through the septum into the reservoir.
[0004] Implantable vascular access ports (VAP) are used in the medical field when recurrent
infusions of therapeutic agents into a patient's circulatory system are required over
extended periods of time. Such VAPs generally include a housing containing a reservoir
and septum, with a catheter extending from the housing.
[0005] US 2004/0073196 discloses a vascular access port with a needle detector. It permits a medical professional
to confirm that the needle has been correctly inserted through the septum and into
the internal reservoir of the VAP. The VAP system notifies the patient and/or medical
professional if the needle has been accidentally withdrawn. The content of
US 2004/0073196 is hereby incorporated by reference thereto in its entirety.
[0006] US 2014/0228765 discloses a refillable and implantable infusion apparatus and method that includes
a needle penetration detector that detects and indicates the position of a needle
relative to a septum of a drug reservoir of the implantable infusion apparatus. With
the needle position data, medical professionals may better ensure they are injecting
drugs into the drug reservoir, thus, improving patient safety. The content of
US 2014/0228765 is hereby incorporated by reference thereto in its entirety.
[0007] Known needle detection systems are designed to work with single-reservoir infusion
devices and vascular access ports. The known systems do not address the complexity
and potential failure modes of more complex multiple-reservoir infusion devices or
VAPs which receive more than one therapeutic agent.
[0008] This is addressed by the method with the features of claim 1.
[0009] A method for filling and/or refilling a multiple-reservoir infusion pump with therapeutic
agents includes the following steps to fill a first reservoir: Selecting a first therapeutic
agent to be filled into a first reservoir of a multiple-reservoir infusion pump. Coupling
a first refill container with the first therapeutic agent with a first refill needle.
The first refill needle has a first needle opening arranged at a first distance dl
from a distal end of the refill needle which, when the first refill needle is fully
inserted into a refill port of the multiple-reservoir infusion pump, is in fluid communication
with the first reservoir. Inserting the first refill needle into the refill port and
delivering, e.g. delivering, the first therapeutic agent from the first refill container
into the first reservoir.
[0010] The method further includes these steps to fill a second reservoir: Selecting a second
therapeutic agent to be filled into a second reservoir of the multiple-reservoir infusion
pump. Coupling a second refill container with the second therapeutic agent with a
second refill needle. The second refill needle has a second needle opening arranged
at a second distance du from the distal end of the refill needle which, when the second
refill needle is fully inserted into the refill port of the multiple-reservoir infusion
pump, is in fluid communication with the second reservoir. Inserting the second refill
needle into the refill port and delivering the second therapeutic agent from the second
refill container into the second reservoir.
[0011] The method may further include determining, with a magnetic field sensor arranged
at the refill port, the orientation and/or intensity of a magnetic field within a
magnetic portion of the first refill needle and the second refill needle and distinguishing,
based on the orientation and/or intensity of the magnetic field, the first refill
needle from the second refill needle.
[0012] The method may also include determining, with the magnetic field sensor, presence
of a magnetic field stronger than a maximum allowable threshold, and disabling the
multiple-reservoir infusion pump in response to detecting the magnetic field stronger
than the maximum allowable threshold. The method may include performing an initialization
measurement to determine a reference measurement value of the magnetic field sensor.
The method may further include determining, with a number of two or more magnetic
field sensors axially spaced at the refill port, the orientation and/or intensity
of an equal number of two or more magnetic fields within magnetic portions of the
first refill needle and the second refill needle. It may then associate information
retrieved from the two or more magnetic field sensors through a look-up table and
communicate information retrieved from the look-up table to an external user interface
device. The external user interface device may be a smartphone, a computer, or a tablet
computer. The external user interface device may provide a real-time indication which
of the lower and upper reservoir is being refilled.
[0013] According to an embodiment a refill needle for an implantable infusion device has
an elongated body extending from a proximal end to a distal end. It includes a first
magnetic portion arranged at a distance dmagnet1 from the distal end, and a second
magnetic portion arranged at a distance dmagnet2 from the distal end. The first magnetic
portion has a selectable first magnetic field orientation and/or intensity to encode
a first bit of information and the second magnetic portion has a selectable second
magnetic field orientation and/or intensity to encode a second bit of information.
[0014] The first and second magnetic field may be axially oriented with magnetic poles axially
spaced from one another within magnetic portion. Alternatively, the first and second
magnetic field may be radially oriented with magnetic poles arranged radially inwardly
and outwardly of one another. Alternatively, the first and second magnetic field may
be diametrically oriented with magnetic poles of each magnetic portion arranged circumferentially
opposite one another.
[0015] The elongated body may be made of molded plastic and the magnetic portion may be
formed by a permanent magnet overmolded within the plastic. The elongated body of
the refill needle may include a plurality of three or more magnetic portions, each
of the three or more magnetic portions being selectively magnetic in a first magnetic
field orientation and/or intensity or a second magnetic field orientation and/or intensity
to store one bit of information.
[0016] The elongated body may include a plurality of circumferentially spaced openings arranged
at a first distance dl or at a second distance du from a distal end of the elongated
body. The elongated body may include a first fluid channel which extends from a proximal
end to an opening at a distance dl from the distal end of the elongated body and a
second fluid channel which extends from a proximal end to an opening at a distance
du from the distal end of the elongated body.
[0017] In an embodiment, an implantable infusion device with which the refill needle is
used includes a housing. A refill chamber is arranged within the housing. The refill
chamber is accessible through a refill port. A self-sealing external septum is disposed
at the refill port and forms an access opening of an upper chamber in the refill chamber.
A self-sealing inner septum is disposed within the refill chamber below the external
septum. The inner septum separates the upper chamber from a lower chamber. One sensor
or a first sensor and a second sensor is/are arranged at the refill chamber. A processor
is operatively connected to the first sensor and to the second sensor. The processor
is configured, in response to signals received from the first sensor and from the
second sensor, to detect a presence of a needle in the refill chamber. The processor
is further configured to associate a position of a needle opening with the lower chamber
or the upper chamber.
[0018] A wireless transmitter may be operatively connected to the processor, and the processor
may be configured to transmit a signal relating to the association of the position
of the needle opening with the lower chamber or the upper chamber to an external device.
[0019] The first sensor may be a contact sensor arranged at a bottom of the refill chamber
and the second sensor may be a Hall effect sensor or a microelectromechanical systems
magnetic field sensor arranged within the housing adjacent to the refill chamber.
[0020] The first sensor and/or the second sensor may measure multiaxially. The first and/or
second sensor may measure one dimensionally, two dimensionally and/or three dimensionally.
This results in an improved intensity measurement of the needle. Furthermore, the
detection of the direction of the needle, i.e. its vector, is improved.
[0021] An alternative single-sensor implantable infusion device may include a housing and
a refill chamber arranged within the housing. The refill chamber is accessible through
a refill port. A self-sealing external septum is disposed at the refill port and forms
an access opening of an upper chamber in the refill chamber. A self-sealing inner
septum is disposed within the refill chamber below the external septum and separates
the upper chamber from a lower chamber. A magnetic field sensor is arranged at the
refill chamber and operatively connected to a processor. The processor is configured,
in response to a signal received from the magnetic field sensor, to detect a presence
of a needle in the refill chamber and to associate, by evaluating an orientation and/or
intensity of a magnetic field at the magnetic field sensor, a position of a needle
opening with the lower chamber or the upper chamber.
[0022] In an embodiment, a system for filling and/or refilling an implantable infusion device
includes an implantable infusing device. The implantable infusion device includes
a refill chamber arranged within a housing. The refill chamber is accessible through
a refill port. An upper chamber is formed within the refill chamber and accessible
through a self-sealing external septum disposed at the refill port. A lower chamber
is formed within the refill chamber. The lower chamber is separated from the upper
chamber by a self-sealing inner septum disposed within the refill chamber. A magnetic
field sensor disposed at a distance dsensor from a bottom of the refill chamber. A
processor is operatively connected to the magnetic field sensor.
[0023] The system further includes a refill needle. The refill needle has an elongated body
extending from a proximal end to a distal end. The needle includes a magnetic portion
arranged at a distance dmagnet from the distal end. A needle opening in fluid connection
with the proximal end is arranged at a distance from the distal end of the elongated
body. A user interface device is in wireless communication with the implantable infusion
device. dsensor is positioned relative to dmagnet, in other words, the distance dsensor
is coordinated relative to dmagnet, or in other words dsensor and dmagnet are adapted
to each other. The magnetic field sensor and the magnet are disposed at approximately
the same height, i.e. dsensor at least approximately equals dmagnet, in particular
0,5 * dmagnet ≤ dsensor ≤ 1,6 * dmagnet, more particular 0,75 * dmagnet ≤ dsensor
≤ 1,5 * dmagnet, more particular 1,0 * dmagnet ≤ dsensor ≤ 1,3 * dmagnet. In one embodiment,
dsensor equals dmagnet. In another embodiment, dsensor is slightly longer than dmagent
so that the magnetic portion passes the sensor when it is inserted. The processor
is configured, in response to a signal received from the magnetic field sensor, to
associate a position of the needle opening with the lower chamber or the upper chamber.
The user interface device is configured to indicate the position of the needle opening
in the upper chamber or the lower chamber.
[0024] The processor may be configured to recognize a correctly inserted needle if a magnetic
field having a field strength above a lower threshold is detected by the magnetic
field sensor. The processor may further be configured to associate a position of the
needle opening with the lower chamber or the upper chamber depending on an orientation
and/or intensity of a magnetic field in the magnetic portion. A refill container filled
with a therapeutic agent may be inseparably connected at the proximal end of the elongated
body.
[0025] The system can not only detect the needle position, but it can differentiate between
needles.
[0026] The magnetic field sensor may be a Hall Effect sensor. Alternatively, or additionally,
the magnetic field sensor may be a microelectromechanical systems magnetic field sensor.
[0027] The implantable infusing device may further include a second magnetic field sensor
disposed at a distance dsensor2 from the bottom of the refill chamber. The elongated
body of the refill needle may include a second magnetic portion arranged at a distance
dmagnet2 from the distal end, wherein in particular 0,5 * dmagnet2 ≤ dsensor2 ≤ 1,6
* dmagnet2, more particular 0,75 * dmagnet2 ≤ dsensor2 ≤ 1,5 * dmagnet2, more particular
1,0 * dmagnet2 ≤ dsensor2 ≤ 1,3 * dmagnet2. The second sensor and the second magnetic
portion may be aligned when the needle is fully inserted into the implantable infusion
device, i.e. dsensor2 = dmagnet2. In another embodiment, dsensor2 is slightly longer
than dmagent2 so that the second magnetic portion passes the second sensor when it
is inserted. The processor may be configured to communicate information relating to
an orientation and/or intensity of a first magnetic field in the magnetic portion
and an orientation and/or intensity of a second magnetic field in the second magnetic
portion.
[0028] The following detailed description of the invention is merely exemplary in nature
and is not intended to limit the invention or the application and uses of the invention.
Furthermore, there is no intention to be bound by any theory presented in the preceding
background of the invention or the following detailed description of the invention.
FIG. 1 shows a system for refilling an implantable infusion device.
FIG. 2 shows an upper chamber refill needle.
FIG. 3 shows a lower chamber refill needle.
FIG. 4 shows a dual chamber refill needle.
FIG. 5 shows another lower chamber refill needle.
FIG. 6 shows another upper chamber refill needle.
FIG. 7 shows an exploded view of FIG. 6
FIG. 8 shows a magnetic portion with axial orientation.
FIG. 9 shows a magnetic portion with radial orientation.
FIG. 10 shows a magnetic portion with diametic orientation.
FIG. 11 shows a magnetic portion with skewed orientation.
FIG. 12 is a perspective cross sectional rendering of a system for refilling an implantable
infusion device.
FIG. 13 is a top view of a system for refilling an implantable infusion device.
FIG. 14 is a cross sectional view B-B of FIG. 13.
[0029] FIG. 1 shows schematically a system for refilling an implantable multi-chamber infusion
device 100 with a housing 110. The implantable infusion device 100 may be an implantable
infusion pump which holds two different therapeutic agents within a refill chamber
120. The refill chamber 120 is divided into an upper chamber 122 and a lower chamber
124. The therapeutic agents may be pumped, over time, from the chambers
122, 124 through an implanted catheter into an administration area where the therapeutic agents
are administered. For example, the implanted infusion device may deliver two alternative
anesthetic agents from the chamber through the catheter to the dorsal horn of the
spinal cord in pain management applications.
[0030] The chambers
122, 124 may be reservoirs which hold a supply of therapeutic agent. In that case, the chambers
122, 124 need to be refilled in certain time periods, for example once every month, or as
needed based on a measured use of each therapeutic agent. The chambers
122, 124 may be sized to hold sufficient therapeutic agent for administration over one month,
after which time they need to be refilled. Refilling the chambers
122, 124 may be performed by injecting a needle
200 through the patient's skin into a refill port
130 of the implanted infusion device
100. For that purpose, the refill port
130 includes a self-sealing external septum
132 which can be penetrated by the needle
200. The self-sealing external septum
132 reseals the chamber upon withdrawing the needle
200 from the chamber. Similarly, the upper chamber
122 and the lower chamber
124 may be separated by a self-sealing inner septum
134.
[0031] Alternatively, the chambers
122, 124 within the refill port
130 may be small and not designed to store a supply of the therapeutic agent but rather
be in fluid connection with separately formed reservoirs or tanks through fluid outlets
142, 144. In an alternative configuration one of the chambers within the refill port
130 may be coupled to a tank of an implanted infusion pump while another chamber is coupled
to an implanted catheter and serves as a catheter access point.
[0032] The upper and lower chamber are preferably filled with different therapeutic agents,
allowing significantly more flexible therapy than single-reservoir implantable infusion
pumps can provide. For example, a first therapeutic agent stored within the upper
refill chamber
122 may be administered during daytime, while a second therapeutic agent stored within
the lower refill chamber
124 may be administered during nighttime. Use of multi-reservoir implantable devices
provides medical professionals unique treatment options, allowing different therapeutic
agents to be administered based on rules programmed in the implantable infusion device.
[0033] The different chambers may be separately refilled by using needles
200 which are specifically configured to refill either the lower chamber
124 or the upper chamber
122. As shown in FIG. 2, an upper chamber refill needle
230 has an upper opening
212 which is positioned at an axial distance
duo from a tip at the distal end
202 of the needle
230. The axial distance
duo is selected such that the upper needle opening
212 is located in the upper chamber
122 when the needle is fully inserted into the refill chamber
120. Preferably, the distance
duo is selected such that the upper needle opening
212 is axially centrally located between the external septum
132 and the inner septum
134 when the needle
230 is fully inserted in the refill chamber
120.
[0034] The self-sealing external septum
132 forms an upper boundary of the upper chamber
122. The self-sealing inner septum
134 forms a lower boundary of the upper chamber
122 and an upper boundary of the lower chamber
124. The external septum
132 and the inner septum
134 may be disc-shaped and held within a cylindrical refill chamber
120. The cylindrical refill chamber
120 may extend from a bottom
113 to the refill port
130 along walls
111. The external septum
132 and the inner septum
134 may be arranged in parallel planes at an axial offset from one another.
[0035] FIG. 3 shows a lower chamber needle
240 configured to refill the lower chamber
124. A lower needle opening
211 is disposed at a distal end of the needle at a distance
dlo from the tip. The distance
dlo should be no longer than the distance from the bottom
113 of the refill chamber
120 to the inner septum
134. The distance
dlo may be selected to be as short as possible.
[0036] FIG. 4 shows a dual-chamber needle
250 which can be used to simultaneous refill the upper chamber
122 and the lower chamber
124. The dual chamber needle
250 for this purpose has both a lower needle opening
211 and an upper needle opening
212. When fully inserted into the refill chamber
120, the lower needle opening
211 is located below the inner septum
134 in the lower chamber
124. The upper needle opening
212 is located above the inner septum
134 in the upper chamber
122. A first fluid channel
231 provides a fluid connection from a proximal end of the needle
250 to the lower needle opening
211. A second fluid channel
232 provides a fluid connection from the proximal end of the needle
250 to the upper needle opening
212.
[0037] While the refill chamber
120 has been shown with only one inner septum
134 and two chambers, one skilled in the art will recognize that more than one inner
septum can be used to separate the refill chamber into three or more chambers. Consequently,
refill needles may be configured to refill more than two chambers by having needle
openings axially spaced so as to be located in between two inner septums to refill
additional chambers.
[0038] One skilled in the art will also recognize that the disclosed implantable infusion
device can be an implantable pump, or an implantable vascular access port which operates
in combination with an external pump.
[0039] Needle detection systems for implantable infusion systems are generally known. Known
systems, however, do not address the complexity and potential failure modes of multi-chamber
systems. In particular, a multi-chamber system requires great diligence during refill
to ensure that each chamber is filled with the correct therapeutic agent. Not only
must a medical processional ensure that the right therapeutic agents are administered
to the patient, but also that each of two or more therapeutic agents is filled into
the correct chamber within a multi-chamber system.
[0040] A multi-chamber infusion system therefore preferably includes a needle detection
and identification system. The needle detection and identification system is based
on one or more sensors which are arranged at the refill chamber
120. A bottom sensor
156 may be arranged a bottom
113 of the refill chamber. The bottom sensor
156 may be a contact sensor, such as a pressure-sensitive switch, to detect that a needle
200 has been fully inserted into the refill chamber
120. In this configuration, the bottom sensor
156 serves only to detect a presence of, but not to identify the needle
200.
[0041] Alternatively, the bottom sensor
156 may be a magnetic field sensor configured to detect a magnetic field associated with
a magnetic portion
220 of the needle. That is, the needle
200 may include within its elongated body
201 a magnetic portion
220. The magnetic portion
220 may be formed by a permanent magnet which is embedded within the body
201 of the needle
200. The permanent magnet may be an axially magnetized permanent ring magnet which has
been overmolded within a needle body
201 made of plastic. In a basic implementation of a needle detection and identification
system a single magnetic portion
220 may interact with a bottom magnetic field sensor
156. The magnetic field sensor
156 may be operatively connected to a microprocessor which is configured to read and
evaluate signals from the magnetic field sensor
156. The microprocessor may thereby detect presence of the needle
200 within the refill chamber
120 when the strength of a magnetic field at the sensor
156 exceeds a threshold. The threshold may be a predetermined fixed value, or may depend
on a magnetic field strength measurement performed before the needle
200 is inserted.
[0042] The magnetic field sensor
156 may further be used to identify and distinguish the needle
200 as being lower chamber needle
240 or an upper chamber needle
230. For this purpose, the upper chamber needle
230 may have a lower magnetic portion
224 in which the magnetic field is polarized opposite to the magnetic field of a corresponding
lower chamber needle
240. As shown in FIG. 2, the upper chamber needle
230 has a magnetic portion
224 with a magnetic north pole arranged towards the distal end of the needle. The corresponding
lower chamber needle
240 shown in FIG. 3 has a magnetic portion
220 arranged at the same distance from the tip of the needle, but with opposite polarity.
The magnetic south pole of the lower chamber needle
240 is at the same distance from the distal end of the needle as the magnetic north pole
of the upper chamber needle
230. A processor (not shown) which is in communication with the bottom magnetic field
sensor
156 can determine whether a needle is fully inserted by checking for a presence of a
magnetic field of sufficient strength irrespective of the polarization of the magnetic
field. The same bottom sensor
156 can be used to identify a needle as a lower or upper chamber needle by determining
the polarization of the magnetic field in the needle.
[0043] As shown in FIG. 1, more than one sensor can be used. For example, an upper magnetic
field sensor
152 and a lower magnetic field sensor
154 may be arranged at the refill chamber
120. The upper magnetic field sensor
152 and the lower magnetic field sensor
154 may include Hall Effect sensor elements or microelectromechanical systems magnetic
field sensor elements. Each magnetic field sensor may include more than one Hall Effect
sensor element or microelectromechanical systems magnetic field sensor elements.,
and may e.g. include two or three Hall Effect sensor elements or microelectromechanical
systems magnetic field sensor elements circumferentially distributed around the refill
chamber at the same or varying axial distance from the bottom
113 of the refill chamber.
[0044] A microelectromechanical systems (MEMS) magnetic field sensor is a small-scale device.
It can detect and measure magnetic fields. Such a sensor may detect effects of the
Lorentz force, e.g. it may electronically measure a change in voltage or resonant
frequency, or it may optically measure a mechanical displacement. Temperature effects
should be compensated for. MEMS magnetic field sensor comprise a variety of parameters,
e.g. a resonance frequency, a mode shape, a responsivity, a quality factor, or a resolution.
[0045] The resonance frequency is the frequency with the highest or longest vibration amplitude
of the MEMS magnetic field sensor. The pattern of the vibration of the sensor is the
mode shape. The size of the oscillation being achieved with the same external condition
is described by the responsivity. The quality factor describes how much energy is
maintained by the resonator during the vibration. The resolution describes the smallest
measurable magnetic field.
[0046] MEMS magnetic sensors are very small and may detect very small magnetic fields. Thus,
a magnetic field measurement by a MEMS magnetic field sensor has a high resolution.
Furthermore, the MEMS magnetic field sensor may be placed close to the source of the
magnetic field, i. e. close to the position refill needle.
[0047] A magnetic field sensor may consist of one or more sensing elements configured to
detect the strength and/or orientation of the magnetic field.
[0048] Use of magnetic field sensors
152, 154 and use of multiple sensor elements per magnetic field sensors allows complex processing
of sensor signals to triangulate and thereby more accurately determine the position
of the needle within the refill chamber.
[0049] Furthermore, the implantable device may comprise more than two magnetic field sensors.
For example, a third magnetic field sensor may determine magnetic field of the surrounding
of the implant and refill port. That third magnetic field sensor may be arranged in
the housing of the implantable infusion device.
[0050] A refill needle may include two or more magnetic portions axially spaced from one
another. Preferably, the axial position of the magnetic portions in the needle corresponds
to the axial position of magnetic field sensors at the refill chamber. As shown in
FIG. 1, the upper magnetic portion
222 of the needle
200 is approximately axially aligned, when the needle is fully inserted, with the upper
magnetic field sensor
152. The lower magnetic portion
224 is axially aligned with the lower magnetic field sensor
154 when the needle
200 is fully inserted.
[0051] Preferably, as shown in FIG. 5, a further lower chamber refill needle
240' is shown. In that example, the lower chamber refill needle
240' may include a lower magnetic portion
224 and an upper magnetic portion
223. A distance element
225, which may be a ball, may space apart the lower magnetic portion
224 from the upper magnetic portion
223.
[0052] A sealing element
226 may separate at least one lower needle opening
211 from the lower magnetic portion
224 and the upper magnetic portion
223. Thus, the lower needle opening
211 is arranged proximal to the lower magnetic portion
224 and upper magnetic portion
223.
[0053] The magnetic field of the lower magnetic portion
224 is polarized opposite to the magnetic field of the upper magnetic portion
222. In that example, the lower magnetic portion
224 comprises a south pole on the proximal end and a north pole on the distal end. The
upper magnetic portion
222 comprises a north pole on the proximal end and a south pole on the distal end.
[0054] A cap
227 is arranged distal to the lower magnetic portion
224. The cap
227 and the sealing element
226 hold the lower magnetic portion
224 and the upper magnetic portion
222 in place.
[0055] The distal end
202 of the refill needle
240' may comprise a central tip. The central tip may comprise three sharpened sides.
[0056] FIG. 6 shows another upper chamber refill needle
230'. In that example, the upper chamber refill needle
230' may include a lower magnetic portion
220 and an upper magnetic portion
222. A distance element
225, which may be a ball, may space apart the lower magnetic portion
220 from the upper magnetic portion
222.
[0057] A sealing element
226 may separate at least one upper needle opening
212 from the lower magnetic portion
220 and the upper magnetic portion
222. Thus, the upper needle opening
212 is arranged proximal to the lower magnetic portion
220 and upper magnetic portion
222. Furthermore, the position of upper needle opening
212 is closer to the proximal end of the upper chamber refill needle
230' than the position of the lower needle opening
211 of the lower chamber refill needle
240'.
[0058] The magnetic field of the lower magnetic portion
220 is polarized opposite to the magnetic field of the upper magnetic portion
222. Furthermore, the polarization is opposite to the example of FIG. 5. In FIG. 6, the
lower magnetic portion
220 comprises a north pole on the proximal end and a south pole on the distal end. The
upper magnetic portion
222 comprises a south pole on the proximal end and a north pole on the distal end. The
polarization of the magnetic portions of the example shown in FIG. 6 is therefore
opposite to the polarization of the magnetic portions of the example shown in FIG.
5.
[0059] A cap
227 is arranged distal to the lower magnetic portion
220. The cap
227 and the sealing element
226 hold the lower magnetic portion
220 and the upper magnetic portion
222 in place.
[0060] The distal end
202 of the refill needle
230' may comprise a central tip. The central tip may comprise three sharpened sides.
[0061] FIG. 7 shows an explosion view of the upper chamber refill needle
230' of FIG. 6. For manufacturing the refill needle, the sealing element
226, the upper magnetic portion
222, the distance element
225, and the lower magnetic portion
220 are pressed into the distal opening of a cannula of the refill needle
230'. The sealing element
226, the upper magnetic portion
222, the distance element
225, and the lower magnetic portion
220 may comprise a diameter being slightly bigger than the diameter of the cannula. In
that case, pressing the sealing element
226, the upper magnetic portion
222, the distance element
225, and the lower magnetic portion
224 into the cannula fixes their position in the refill needle.
[0062] The cap
227 may be pressed into the distal opening of the cannula to fix the input in the cannula.
However, the cap
227 may also be fixed in the cannula by another method.
[0063] Then, the central tip is pressed into the distal opening at the distal end
202 of the refill needle. Alternatively, the central tip may be glued or welded into
the distal opening at the distal end.
[0064] The manufacturing mentioned above also applies to the lower chamber refill needle
240'.
[0065] The configuration of the magnetic portions
220, 222 of the examples in FIGs. 5 and 6 results in a magnetic field at the distance element
225 that is turned by 90° with respect to the sensor. This means, when inserting the
refill needle into the infusion device the orientation of the magnetic field lines
will turn from a direction parallel to the axis of the refill needle to a direction
orthogonal to the axis of the refill needle. This allows the sensor to detect the
position of magnetic field which is in close alignment to the distance element
225 with high accuracy.
[0066] The refill needle may comprise an outer diameter in the range from 0.4 mm to 1.0
mm, preferably of 0.7 mm. An inner diameter of the refill needle may be in the range
from 0.2 mm to 0.8 mm, preferably 0.5 mm.
[0067] A diameter of the needle opening may be in the range from 0.1 mm to 0.7 mm, preferably
0.35 mm. The distance of the center of the needle opening from the central tip may
be in the range of at least 6.0 mm to 80.0 mm.
[0068] A diameter of the distance element
225, the upper magnetic portion
222, and the lower magnetic portion
224 may be in the range between 0.2 mm to 0.6 mm, preferably 0.4 mm. A distance of the
distance element
225 from the central tip may be between 2.0 mm and 3.7 mm, preferable 3.15 mm.
[0069] Various magnetic field configurations can be employed for the magnetic portion
220. For example, as shown in FIG. 8, the magnetic field can be axially oriented with
magnetic poles axially spaced from one another within magnetic portion. Alternatively,
as shown in FIG. 9, the magnetic field can be oriented radially with magnetic poles
arranged radially inwardly and outwardly of one another. As shown in FIG. 10, the
magnetic field can be diametrically oriented with magnetic poles of each magnetic
portion arranged circumferentially opposite one another. As shown in FIG. 11 the magnetic
field can be skewed.
[0070] While FIGs. 9 and 10 show two-pole configurations of the straight and skewed magnetization,
multi-pole configurations can also be used.
[0071] Furthermore, FIGs. 8 to 11 show magnetic portions comprising bores in axial direction.
However, those bores are optional. Thus, the magnetic portions as shown in FIGs. 8
to 11 may be free from bores.
[0072] Use of two or more magnetic portions
220, 222 within a needle allows encoding two or more bits of information. For example, when
using axial magnetic field orientations one bit of information can be encoded by choosing
a "distal north" or "distal south" configuration. Similarly, one bit of information
can be encoded in a radial magnetic field orientation by choosing a "outside north"
or "outside south" configuration. The relative circumferential orientation of diametrically
oriented magnetic fields can be used to encode one or more bits of information. Absence
of a magnetic field can be used to encode information. Information magnetically encoded
within the needle may be used to identify the needle, for example to recognize a needle
as an upper or lower chamber needle. Additional information may be magnetically encoded
within the needle and associated with a look-up table stored within a processor in
the infusion device or an external device which is in wireless communication with
the infusion device. The additional information may be used to eliminate further potential
failure modes. For example, the needle may be firmly and inseparably attached to a
refill reservoir which is prefilled with a therapeutic agent. In that case, the needle
can be encoded to identify the therapeutic agent. The infusion device may, through
its two or more magnetic field sensors, read information magnetically encoded within
the needle and communicate the information to an external device. A processor within
the infusion device may be programmed to provide an alert if an incorrect needle is
inserted into its refill chamber. For example, the infusion device may be programmed
to recognized that is should be filled with a therapeutic agent
A in the lower refill chamber
124 and a therapeutic agent
B in the upper chamber
122. If a needle encoded to be associated with a therapeutic agent
C is inserted into the refill chamber
120 an alert is issued. Similarly, an alert is issued if an upper chamber needle
230 encoded to contain therapeutic agent
A is inserted, alerting a medical processional to the incorrect association of agent
and chamber.
[0073] The infusion device may include a feedback actuator, e.g. a vibration element, to
communicate the correct or incorrect insertion of a needle directly to a patient,
e.g. through haptic feedback.
[0074] During refill, a lower magnetic portion
224 of the needle
200 may interact with an upper magnetic field sensor
152 which is arranged near the external septum
132. In particular, two or more Hall Effect sensors or microelectromechanical systems
magnetic field sensors
152 arranged at the refill port
130 can be used to triangulate a position of the needle
200, ideally even before piercing a patient's skin to properly position the needle centrally
within the refill port
130. For this purpose, the processor may evaluate a field strength of a magnetic field
at two or more Hall Effect sensors or microelectromechanical systems magnetic field
sensor elements and provide, through an external user interface device, positioning
instructions to achieve equal field strengths at all sensors. For that purpose the
implantable infusion device may include a wireless transmitter operatively connected
to the processor.
[0075] The upper magnetic field sensor
152 and the lower magnetic field sensor
154 need not be sensitive in the same plane. For example, the upper magnetic field sensor
152 can be configured to sense a radially oriented magnetic field in an upper magnetic
portion
222 of the needle
200. The lower magnetic field sensor
154 may at the same time be configured to sense an axially oriented magnetic field of
the lower magnetic portion
220. Of course, magnetic field sensors can be configured to sense multiple different magnetic
field orientation and/or intensities, so that the type of magnetic field (axial, radial,
multi-pole, etc.) can be used to encode further information within the needle
200.
[0076] It can be beneficial to maximize the information derived from each magnetic field
sensor
152, 154 by evaluating its sensors output over time and thus analyzing a change in the magnetic
field around the sensor as an encoded needed is inserted into the refill port
130. A processor connected to the magnetic field sensors
152, 154 may e.g. sample a sensor output multiple times per second to determine a maximum
field strength of the magnetic field around the sensor, or a length of a magnetic
portion of the needle. A number of n≥1 magnetic field sensors may be used to analyze
a greater number of m≥1 magnetic portions of a needle.
[0077] One or more magnetic field sensors of the infusion device can be used to detect presence
of a strong magnetic field indicative of the device being within a MRI device. The
processor may be configured to, upon detecting an excessive magnetic field, shut down
pumps and/or close valves within the device to prevent incorrect dosage of therapeutic
agents while the device is exposed to the magnetic field of an MRI device.
[0078] Referring now to FIGs. 12-14, different views of a port for an implantable infusion
device
100 are shown. The implantable infusion device
100 may combine aspects of an implantable infusion pump with aspects of a catheter access
port (CAP) with a single port
130. The infusion device
100 here includes a relatively narrow generally cylindrical port chamber
120. As shown, the diameter of the port chamber
120 is only slightly larger than the diameter of the refill needle
200. The diameter of the port chamber
120 may be less than two times the diameter of the refill needle, less than 1.5 times
the diameter of the refill needle, or even less than 1.2 times the diameter of the
refill needle.
[0079] To introduce the needle in the port chamber
120 an external port guide
131 is provided. The external port guide
131 has a frustoconical shape which terminates into a cylindrical opening. The external
port guide
131 is generally shaped and functional like a funnel. An outer diameter of the external
port guide
131 may be more than 10 times, more than 20 times, or even more than 30 times greater
than the diameter of the needle
200. The external septum
132 is arranged at the lower, inner end of the external port guide
131.
[0080] The external septum
132 may be a disk-shaped mass of silicone held within a widened portion of the port chamber
120 between an upper wall and a lower wall. The upper wall may be the part of the external
port guide
131. An external septum cavity
137 may be formed below the external septum
132 with a diameter smaller than the diameter of the external septum
132, yet significantly larger than the diameter of the needle
200.
[0081] Fluid outlets
142, 144 are arranged perpendicularly to a longitudinal axis of the port chamber
120. A first fluid outlet, e.g. the lower fluid outlet
144, may be directly coupled to an implanted catheter. In respect to the lower fluid outlet
the implanted infusion device
100 thus acts as a catheter access port, e.g. a vascular access port, which can be used
to administer a therapeutic agent while the needle
200 is inserted into the port and externally supplied with the therapeutic agent.
[0082] A second fluid outlet, e.g. the upper fluid outlet
142, may be in fluid communication with a refillable tank of an implanted infusion pump.
The tank may be formed as a bellows which expands and contracts with an amount of
therapeutic agent therein.
[0083] One or more magnetic portions
220 of the refill needle may be arranged towards the distal end of the needle
200 below the lowest fluid opening. In this case, the magnetic portion
220 can be formed by a solid cylindrical magnet which is inserted into a hollow space
within the needle
200. One or more magnetic field sensors
154 may be arranged proximal to the bottom of the port chamber below the lower chamber,
spaced from the bottom so as to approximately align with the magnetic portion
220 of the needle
200. Two or more magnetic field sensors (not shown) can be stacked along the axial extension
of the needle within a sensor chamber
151 at a lower end of the refill port
130.
[0084] The refill port
130 may be made of separately machined portions
161, 162, 163 which are stacked on top of one another and held together by screws
165. As shown, the external septum
132 may be held within an upper portion
161 of the port
130. The inner septum
134 and the upper fluid outlet
142 may be arranged within a center portion
162 of the refill port. The lower fluid outlet
144 may be arranged within a lower portion
163 of the port
130. Septum cavities
137, 138 may be formed at upper ends of the center portion
162 and lower portion
163 to hold the respective septum within the portion above, and provide a space for the
septum to expand into when the needle
200 is inserted into the septum.
[0085] Throughout this specification and the following claims the indefinite article "a"
or "an" means "one or more". Reference to "a first element" does not mandate presence
of a second element.
[0086] While the present invention has been described with reference to exemplary embodiments,
it will be readily apparent to those skilled in the art that the invention is not
limited to the disclosed or illustrated embodiments but, on the contrary, is intended
to cover numerous other modifications, substitutions, variations and broad equivalent
arrangements that are included within the spirit and scope of the following claims.